Channel connections between a PSTN and IP network can be divided into two parts: signaling channel connections and payload channel connections. The network element, called gateway, between the PSTN and the IP network comprises a control part and a cross-connection part. The control part, which can be a separate element from the network element, receives the signaling, called SS7, from the PSTN network, converts it to the signaling used in the IP network, for example H.323, and vice versa. The control part also controls operations in the cross-connection part. The cross-connection part reserves and connects payload channels from PCM time-slots (a PSTN network) to IP packet streams (an IP network) and vice versa.
The control part has a unique SPC (Signaling Point Code) number for the needs of the SS7 signaling. Due to this, there is one control part per a cross-connection part. The cross-connection part of the gateway can also be divided into several units, each unit including a portion of the PSTN and IP channels. Each unit needs a separate control part. So, for example, a gateway with three cross-connection units needs three control parts. However, sometimes there are needs, such as cost-saving and maintenance, for using several cross-connection units under one control part. The objective of the invention is to make it, possible. This is achieved in a way described in the claims.